Electric circuit interrupter



P 1937. D. c. PRINCE ET AL 2,092,656

ELECTRIC CIRCUIT INTERRUPTER Filed Aug. 1, 1936 Inventors: David C. Prince, WHFred R SKeatS by #m vz./ 1

The]

Attorne Patented Sept. 7, 1937 UNITED STATES PATENT OFFICE David 0. Prince, Swarthmore, Pa., and Wilfred F. Skeats, Scotia, N. Y., assignors to General Electric Company, a

corporation of New York Application August 1, 1936, Serial No. 93,872

6 Claims.

Our invention relates to electric circuit interrupters, more particularly to high tension circuit breakers of the well known explosion cham ber type wherein pressure generated by arcing within a pressure confining chamber containing an arc extinguishing liquid is utilized to direct liquid through the path of the arc.

The explosion chamber type of circuit breaker has been and is extensively used for the interruption of high tension power circuits due to the fact that the arc length and hence the arcing time are quite definitely controlled. That is, in a well known form of explosion chamber breaker, for example, the arc is generally extinguished at least by the time the movable contact clears the exhaust port of the explosion chamber. Notwithstanding this limitation of the arc length, it is often desirable in high voltage installations to interrupt a power circuit of commercial frequency within several half cycles of arcing, that is before the movable contact even clears the exhaust port of the explosion chamber.

l-Ieretofore, various cross-blast arrangements having exhaust ports communicating with the chamber and extending transversely of the are have been tried in connection with the interruption of high tension power circuits but it has been found that at high voltages, such as 220 kv. for example, the interrupting performance is not satisfactory apparently due to voltage creepage breakdown along a path paralleling the exhaust ports.

The principal object of our invention is the provision of an improved high tension explosion chamber type circuit interrupter which is effective to shorten the arc length by interrupting the are well Within the chamber.

Our invention. will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize our invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawing, the single figure thereof shows an elevational View, partly in section, of the contact and are extinguishing structure of one pole of a high tension explosion chamber type circuit breaker embodying the present invention.

The high tension explosion chamber type circuit breaker illustrated comprises relatively movable contact structure, including a fixed contact i, an intermediate or floating contact 2 and a movable rod contact 3 coacting within a pressureconfining chamber formed by a so-called explosion pot 4. The explosion pot is of insulating material, such as a laminated structure impregnated with an artificial resin, and is designed to withstand high bursting pressures. The contact and explosion chamber structures above referred to are immersed in a suitable arc extinguishing liquid such as oil.

An insulating plate !5 having apertures 6 sup ports and guides the contact 2, the pot 4 and plate l5 being clamped with respect to a stationary conducting housing i by a clamping means generally indicated at 8. The lead-in conductor 9, which is provided with an insulating bushing at I0, is electrically connected to the housing I in which is mounted the fixed contact I. The contact I is mounted for limited vertical movement on the guide rod I l and is resiliently biased by a spring l2 to a lower limiting position as shown. A flexible connection l3 interconnects contact i and housing I.

The circuit breaker so far described is of the so-called oil blast type wherein an initial or pressure generating are formed between fixed contact i and the intermediate contact 2 causes a blast of oil through the arc path at the exhaust port 4 of the explosion chamber when the movable rod contact 3 has cleared this port during its downward circuit opening movement. A detailed description of the operation of the oil blast type of circuit breaker is believed unnecessary for a complete understanding of the present invention, other than to point out that in the closed circuit position the movable rod contact 3 is elevated until it forces the intermediate contact 2 against the bias of its spring 2' to engage contact I. Conversely, when the circuit is opened, separation of the contacts I and 2 occurs previous to separation of contacts 2 and 3 for the purpose of generating pressure within the explosion pot and for causing interruption of the main are at the exhaust port 4.

For the purpose of interrupting the are within the explosion pot and for shortening the duration of arcing between the contacts 2 and 3, there are provided a plurality of insulating passages disposed along and transversely of the arc path. That is, these insulating exhaust passages vent the interior of the explosion pot at points spaced along the arc path. Also, in accordance with our invention, the voltage creepage distance between the inner openings of the exhaust passages is made much greater than the straight-line dis- 1 tanoe between said openings.

To this end, the explosion pot 4 is provided with a plurality of tubes [4 of suitable insulating material, such as hard fibre for example, each tube extending through and being secured in the side Walls of the explosion pot 4 as indicated at M. The insulating tubes, each of Which forms an exhaust passage from the interior of the explosion pot, are arranged so that the inner open ends are adjacent and along the arc path between the contacts 2 and 3.

In order to prevent combining of the conducting gas bubbles formed at the outer ends of these tubes, which could cause flash-over, the outer ends are separated by placing the tubes in an angular relationship with respect to each other as illustrated in the drawing. The four tubes, shown by way of example, are arranged in angular radial relationship with respect to the arc path, the upper and lower tubes having an angular relationship of approximately 90.

With this arrangement, for example, a comparatively large number ofexhaust ports can be disposed closely adjacent the main arc path throughout its length within the explosion pot. The individual insulating tubes, which extend an appreciable distance from the side wallsof the explosion pot 4% towards the arc, inherently provide a large voltage creepage surface between passages by reason of the tube surfaces which extend transversely of the arc.

In. operation, opening movement of the rod contact $3 first causes an are between contacts l and 2. Ihe pressure generated within the oil by this are is transmitted through the plate opening (5 to the interior of the pot 4 where it causes expulsion of oil from the pot through the insulating tubes M. Accordingly, as the rod 3 separates from contact 2 at the limiting position shown, the main arc will first be subjected to a transverse jet of oil through the upper tube, which is preferably positioned adjacent the point of contact separation. As the contact 3 is lowered, the arc is subjected to subsequent jets of oil through the other tubes as the arc is drawn opposite the openings thereof. If desired, the tubes M may be positioned so closely with respect to the movable contact that. the contact successively uncovers the openings of the tubes as it moves to open circuit position.

It should be noted that the arc, instead of being drivencontinuously in one direction by a trans verse blast, is subjected to succeeding blasts, each or which tends to drive a portion of the arc in a different direction and into one of the insulating passages. The tendency is, therefore, to disrupt the are along its entire length.

Although in practice the arc is generally interrupted well within the explosion pot, due to the fact that during the initial circuit opening movement the pressure can be relieved only through the tubes Hi, there will in'addition be an interrupting blast at the explosion chamber exhaust l when the contact 3 clears the exhaust port.

It should be understood that our invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of our invention.

What we claim is new and desire to secure by Letters Patent oi the United States:

1. An electric circuit interrupter comprsing a pressure confining chamber containing an arcextinguishing liquid, circuit controlling means arranged to form an are within said chamber, and means forming a plurality of insulating passages arranged opposite the path of said are to exhaust exteriorly of said chamber, the insulating means forming said passages extending an appreciable distance within said chamber and having a creepage surface extending approximately twice said distance substantially transversely of said are so that the path for voltage creepage breakdown at said passages is great as compared with the distance between the passage openings adja cent said arc.

2. A high tension electric circuit breaker comprising a pressure confining chamber containing an arc-extinguishing liquid, relatively movable 5 contact structure arranged upon opening of the circuit to form an are within said chamber, and means including a tubular member forming an insulating passage arranged laterally of the path of said are to exhaust exteriorly of said chamber, l0 said tubular member extending within said chamber and having an appreciable creepage surface extending substantially transversely of said are towards the side walls of said chamber.

3. A high tension electric circuit breaker com 15 prising a pressure confining chamber containing an arc-extinguishing liquid, relatively movable contact structure arranged upon opening of the circuit to form an arc within said chamber, and a plurality of insulating tubes forming passages opposite the path of said are to exhaust exteriorly of said chamber, said insulating tubes extending within said chamber from the side walls thereof to a position substantially transversely of the path of said arc so as to provide a comparatively long path for voltage creepage breakdown with respect to the tube openings adjacent said arc.

4. A high tension electric circuit breaker comprising a pressure confining chamber containing an arc-extinguishing liquid, relatively movable 39 contact structure arranged upon opening of the circuit to form an are within said chamber, and means forming a plurality of insulating passages arranged oppositely the path of said are to exq haust exteriorly of said chamber, the openings of said passages adjacent said are being disposed generally along a portion of a helix with respect to said are so that said passages exhaust in angular radial directions.

5. A high tension electric circuit breaker of the oil blast type comprising a pressure-confining chamber containing an arc-extinguishing liquid, relatively movable contact structure arranged to form a pressure generating arc and a main are within said chamber, and means forming a plurality of insulating passages arranged transversely of the path of said main arc to exhaust exteriorly of said chamber, the inner openings of said passages being spaced along the path of said main arc adjacent thereto whereby, arc pressure in said chamber causes flow of arc-extinguishing liquid transversely through said main are into said passages, the insulation means extending between and forming said passages having a voltage creepage surface extending in part substantially transversely of said main are so that no path for voltage creepage breakdown exists in parallel relation to the passage openings adjacent said main arc.

6. An electric circuit interrupter comprising an explosion pot containing an arc-extinguishing liquid, circuit controlling means arranged to form an arc within said pot, and a plurality of insulating tubes positioned in and extending through s the wall of said pot, said tubes forming exhaust passages venting the interior of said pot, the inner ends of said tubes extending an appreciable distance from the wall of said pot and being disposed adjacent and along the path of said arc.

. DAVID C. PRINCE.

WILFRED F. SKEATS. 

